Lejeunea dimorpha, an obligate epiphyll taxon, differs from all other species in the genus Lejeunea by the development of cladia (specialized caducous branches) (Fig. 1C) as a type of vegetative propagation (Kodama 1976, Pócs et al. 1995, Lee 2013, Lee & Gradstein 2013). The leaves of such cladia are morphologically different from those on the main shoot or on other vegetative branches by having numerous marginal rhizoids on the margins (Fig. 1D, E). Furthermore, these cladia also have very large underleaves and the stems are very fragile and caducous. These cladia usually bear 3–5(10) pairs of leaf lobes and 3(7) large underleaves (Lee 2013), however, the Papua New Guinean specimen can bear 18 pairs of leaf lobes and 15 large underleaves. Other distinguishing characters of L. dimorpha are the broadly rounded leaf lobes, the oil bodies are glistening-homogenous, Massula - type, smooth and rarely segmented, the leaf cells have well-developed trigones, the basal cells with 2(3) conspicuous intermediate thickenings between adjacent trigones, and the obovoid perianth with 5 keels and 2–3 cells long beak (Lee 2013).

Specimen examined: the Philippines, Mindanao: Davao, Sibula. Warburg, July 1888, in Verdoorn Reliquiae No.388 (EGR, dupl. ex NY).

Habitat: This species grows exclusively on living leaves.

Illustrations: Kodama (1976), Lee (2013).

Range: Vietnam (Shu et al. 2017), Peninsular Malaysia, Borneo (East Malaysia: Sabah, Kalimantan), Papua New Guinea and the Philippines (Mindanao*).